1. Field of the Invention
The present invention relates to a method of transmitting monitor/management information in a data communication network constructed by connecting a plurality of communication devices, for realizing a communication between a plurality of data terminals such as personal computers. The present invention also relates to the communication device in the network. The monitor/management information includes information on the causes of disconnections of lines between the communication devices and other information, such as identification numbers of the communication devices, the type of communication devices, set conditions in the communication devices, and the data and time of events occurring in the communication devices.
2. Description of the Related Art
The aforementioned data communication network has been enlarged, given a higher performance, and has had various functions added thereto, and thus a unified monitoring and/or management of the network is now required.
Also, many different types of communication devices constitute the network. Namely, not only communication devices connected through a private line or a leased line but also communication devices connected through a public switched network or a switched network are used, and therefore, a monitoring and/or management of the communication devices connected through the switched network is required.
In a network including only communication devices connected through a private line or leased line, a unified monitoring/management of the network has been realized by communicating monitor/management data between first communication devices connected to a host for monitoring/management and second communication devices connected through that line to the first communication devices, independently of a user data communication between the communication devices, whenever the host or the communication devices requires same and as long as they are normally operating. Usually, the communication of the monitoring/management data is carried out by using a lower frequency band than that of the user data communication, within a frequency band of the communication line.
Nevertheless, in a network including the second communication devices connected through the switched network, since repeated connections and disconnections between the communication devices occur in the switched line as time elapses, the second communication device cannot communicate the monitoring/management data to the host except when the second communication device is connected through the switched network to the first communication device connected to the host. Thus, when a disconnection between the communication devices occurs, the communication device cannot communicate the cause of disconnection to the host after the disconnection, even if the device can detect same.
Generally, the cause of the disconnection is due the following factors i) to iv), and the factors i) to iii) can be detected by the communication device:
i) normal disconnection by a disconnection control signal from a data terminal connected to a communication device; PA1 ii) manual disconnection using a switch provided in a communication device; PA1 iii) spontaneous disconnection by a communication device when the communication device detects a deterioration of a line such that a normal data communication cannot be maintained; and
iv) sudden disconnection caused by an obstruction.
In addition, as mentioned before, communication of the monitoring/management data can be carried out only during the user data communication, by utilizing a lower frequency band. The user data communication is carried out as required by the user, because the user fears the expense thereof. On the other hand, a predetermined communication time dependent or a throughput of the host and the communication device, a delay time in the transmitting line, and a transmission rate, are required for the communication of the monitoring/management data, and therefore, the communication of the monitoring/management data may be broken off before it is completed.